Lester said the smoke from the fire at Hazelwood open-cut coalmine, which has been burning since 9 February, was still a long way off levels needed to trigger an evacuation. She added that there was no evidence of long-term health effects from a short-term exposure to smoke and ash.

Speaking in nearby Traralgon, Lester said: “We don’t believe there’s a necessity to evacuate. We haven’t seen levels rise to anywhere near a level where we would be concerned.”

Fire crews are hoping to have the blaze put out in two weeks but the fire services commissioner, Craig Lapsley, conceded it could be months if conditions were not favourable.

High temperatures and winds forecast next Thursday could create severe fire danger, he said, posing another challenge.

Lapsley was also concerned that battling the blaze could cause a landslide at the mine. “The fact is that as we put water in, we potentially erode parts of it,” he said. “That’s a key consideration for our people. We do not want a landslide in that mine.”

Residents are shocked that the fire was deliberately lit. “I cannot understand what you gain through doing something as terrible as that to affect so many people’s lives,” said one resident, Andrea Camier.

Sharon Dale, who works in Morwell, said she was appalled to learn that an arsonist was to blame. “It’s just disgusting. There’s so many people sick from it now, and the smoke and the fumes. It’s just really bad. It’s the smell of the coal that’s the worst thing.”